This following project is an NIH Mentored Clinical Scientist Research Career Development Award (K08) application for Dr. Christopher Lux, an Acting Instructor in the Department of Pediatrics at the University of Washington (UW). Dr. Lux has completed his clinical training in Pediatric Hematology Oncology and Bone Marrow Transplant and is committed to a career as a physician-scientist focused on the treatment of hemoglobinopathy patients. Dr. Lux's specific research interest is the generation and testing of gene editing tools to modify the hemoglobin locus within hematopoietic stem cells for autologous transplant. His long-term career goal is to establish himself as an independently-funded principle investigator developing gene therapy solutions for patients and aiding in their ethical and safe introduction to clinical use. In order to achieve this goal, Dr. Lux is requesting NIH K08 support for additional training and mentorship in the following specific areas: (1) additional training in gene editing of human and non-human primate hematopoietic stem cells and repair template design and delivery; (2) additional training in bioethics as it relates to emerging gene editing technologies; (3) additional training in clinical trials design and implementation; (4) attendance of scientific conferences, career development seminars, and additional classroom-based training relevant to this project; and (5) mentorship regarding successful transition to scientific independence. Dr. Lux proposes research efforts to achieve further his initial progress in developing a therapeutic gene editing approach for the treatment of hemoglobinopathy patients including: Aim 1) developing procedures to express therapeutic levels of hemoglobin by site specific modification of the ?-hemoglobin promoter using homology- directed-repair (HDR) donor templates; Aim 2) assessing the ability of HDR edited human cells to engraft in immunodeficient mice and to allow for chemo-selection; and Aim 3: utilizing the non-human primate system to assess the potential for HDR edited CD34+ cells to approximate the clinical performance of these tools without a xenograft barrier. Aims 1&2 will be carried out primarily at the Seattle Children's Research Institute under the mentorship of Dr. David Rawlings. Aim 3 will be carried out primarily at the Fred Hutchinson Cancer Research Center under the mentorship of Dr. Hans-Peter Kiem. Both mentors have significant track records for training physician scientists and developing new therapies. The proposed studies offer a potential path to site specific gene editing and chemo-selection as a means for a treating the most common single gene disorders in man. These studies will be expected to yield publications and the preliminary data required for independent R01 funding.